This invention relates to the use of certain siloxane and silane materials for the conservation of organic and inorganic materials. More specifically, this invention deals with a method of impregnating organic and inorganic materials with siloxanes and silanes and ultimately curing such materials to provide preservation properties to such materials. An especially significant use of the method is to preserve and conserve ancient artifacts.
Plastination and/or conservation are terms that are often used in this art to denote the preservation of perishable biological specimens, especially soft, putrifiable materials with high water content. During the plastination method, water, and part or all of the fat (if present), are replaced by a curable resin system or elastomer system in order to optimize the preservation of the materials and to optimize the natural appearance of the material or enhance its aesthetic appearance.
Plastination is utilized therefore, in the preservation of whole body organs and bones, both animal and human, for pathological and anatomical studies; in zoology for the plastination of small animals, such as beetles, spiders, frogs, and reptiles, such as turtles, salamanders; in botany, for fungus and higher plant specimens; archeology for the preservation of wood, ceramics, pottery, glass, leather, jewelry, and the like.
Preservation techniques have also been used in the treating of books, newspapers, photographs and materials of a like nature.
Plastination utilizes many different curable materials, for example, polyepoxides, polyesters, silicone rubbers, and the like.
The inventors herein are aware of several patents which show the use of certain materials for plastination processes.
For example, U.S. Pat. No. 2,106,261, which issued Jan. 25, 1938 to Weidemann deals with a process in which the specimen which is to be treated is immersed in bleach. The specimen is then washed with water to remove essentially all of the bleach and the specimen is set in a dehydrating solution of alcohols, acetone or combinations thereof. Finally, the specimen is dried and coated with a clear lacquer to impregnate or encapsulate the specimen. There is no clear definition of the make up of the clear lacquer.
U.S. Pat. No. 4,205,059 which issued on May 27, 1980 to Von Hagens uses a more elaborate process in which the process starts out with the replacement of the water content of the specimen, in this case, animal or vegetable tissue, with an organic solvent which is volatile in a vacuum and at ambient temperature. Then, the specimen, which contains solvent, is held in contact with a fluid precursor polymer system in a vacuum and at a specified temperature until the solvent is volatilized and replaced in the specimen by the polymeric system. The curable system is stated as being capable of being polymerized into a solid, water insoluble, synthetic resin. The specimen to then subjected to a xe2x80x9cdrying downxe2x80x9d time in which the excess polymeric system is allowed to flow by gravity from the specimen. The specimen is then held under polymerization conditions until the resin is cured. Claim 6 of that reference discloses that the resin is xe2x80x9ca silicone rubberxe2x80x9d. The curable silicone rubber was described as a fully compounded curable material.
U.S. Pat. No. 2,244,992 which issued Jan. 13, 1981 to Von Hagens is a divisional of the aforementioned U.S. patent and therefore does not need additional discussion herein.
U.S. Pat. No. 4,278,701 which issued Jul. 14, 1981 to van Hagens, disclaimed the ""059 patent, and the subject matter therein is the same as the ""059 patent except that it does not disclose the xe2x80x9cambient temperaturexe2x80x9d limitation of the ""059 patent.
U.S. Pat. No. 4,320,157 which issued Mar. 16, 1982 is directed to a method of converting cut sections of bio tissue into examinable plastinated sheet by a method which includes pre-treating to render the specimen suitable for impregnation, thereafter, impregnating with a fluid precursor, compressing the specimen between two parallel panels, filling the resulting formation with impregnating fluid, curing the fluid and removing the plates.
This invention deals with new and novel methods of conserving and preserving organic and inorganic materials through the use of novel processes not heretofore found in the prior art.
With more specificity, this invention deals in one embodiment with a method of conserving organic and inorganic materials, wherein the method comprises (I) impregnating a material selected from (a.) organic materials and (b.) inorganic materials with a curable polymeric system comprising (i) a siloxane polymer or a mixture of siloxane polymers having an average of at least two silanol groups per molecule and (ii) sufficient crosslinker or a mixture of crosslinkers to crosslink a significant portion of the siloxane polymer or mixture of siloxane polymers (i), and thereafter, (II) exposing the product of (I) to a catalyst or a mixture of catalysts for a time sufficient to initiate the cure of to the product of (I), wherein the crosslinkers are selected from the group consisting of hydrolyzable silanes having the formula RSi(ORxe2x80x2)3 wherein R is selected from the phenyl group, hydrogen, vinyl, or an alkyl group having from 1 to 12 carbon atoms and Rxe2x80x2 is selected from hydrogen, vinyl, or an alkyl group having from 1 to 8 carbon atoms.
Yet another embodiment is a method in which the product of (II) is subjected to a treatment to cure the curable system formed by the siloxane polymer and the crosslinker of this method.
Still further, another embodiment of this invention is a method of preserving organic and inorganic materials, the method comprising a step (I) in which a material selected from (a.) organic materials and (b.) inorganic materials, is impregnated with a crosslinker or a mixture of crosslinkers sufficient to crosslink a significant portion of a siloxane polymer or a mixture of siloxane polymers having an average of at least two silanol groups per molecule; (II) thereafter, impregnating the product of (I) with siloxane polymer or a mixture of siloxane polymers having an average of at least two silanol groups per molecule, and (III) thereafter, exposing the product of (II) to a catalyst or a mixture of catalysts for a time sufficient to initiate curing of the product of (II).
As in the first embodiment, this process can be extended to include a step to cure the product of (II).
Another embodiment of this invention is a method of preserving organic and inorganic materials, wherein the method comprises (I) impregnating a material selected from (a.) organic materials and (b.) inorganic materials with a siloxane polymer or a mixture of siloxane polymers having an average of at least two silanol groups per molecule and (II) thereafter, impregnating the product of (I) with a crosslinker or a mixture of crosslinkers sufficient to crosslink a significant portion of the siloxane polymer or a mixture of siloxane polymers having an average of at least two silanol groups per molecule. Thereafter, (III), exposing the product of (II) to a catalyst or a mixture of catalysts for a time sufficient to initiate curing of the product of (II).
As before, an additional step can be used which subjects the specimen, that is treated by this method, to a curing step.
Turning to another embodiment of this invention, it has been discovered that the method embodied in the first embodiment can be modified to a method of preserving organic and inorganic materials, wherein the method comprises (I) impregnating a material selected from organic materials and inorganic materials with a cyclosiloxane or a mixture of cyclosiloxanes having an average of at least two silane hydrogens per molecule and thereafter, exposing the product created thereby to a catalyst or a mixture of catalysts for a time sufficient to initiate curing of the product. As before, an additional step can be used which subjects the specimen, that is treated by this method, to a curing step.
Still further, an embodiment of this invention is the substitution of essentially linear methylhydrogen siloxanes for the cyclic siloxanes of the method just supra and such a method preserves organic and inorganic materials using a non-cyclic siloxane or a mixture of non-cyclic siloxanes having an average of at least two silane hydrogens per molecule and having a molecular weight of 5000 g/mole or less, and thereafter, exposing the product obtained thereby to a catalyst or a mixture of catalysts for a time sufficient to initiate curing of the product. Once again, it should be apparent to those skilled in the art upon a close reading of this specification that a further step of curing the product can be utilized in this method.
A further embodiment of this invention is a method of preserving organic and inorganic materials wherein the method comprises impregnating a material selected from organic materials and inorganic materials with a siloxane polymer or a mixture of siloxane polymers having an average of at least two silanol groups per molecule and thereafter, exposing the product obtained thereby to a catalyst or a mixture of catalysts for a time sufficient to initiate curing of the product of (I) and if desired, completing the method with a curing step.
There is also a unique method embodied within this invention which is a method of preserving organic and inorganic materials, in which the method comprises impregnating a material selected from organic materials and inorganic materials with a hydrolyzable silane or a mixture of hydrolyzable silanes and thereafter, exposing the product obtained thereby to a catalyst or a mixture of catalysts for a time sufficient to initiate curing of the product and then, if desired, completing the method by curing the product. Preferred for this unique method is the crosslinker tetraethylorthosilicate. Further, this method can be additionally modified by the use of alkoxysilanes in conjunction with the orthosilicate, which alkoxy silanes, or mixtures of alkoxysilanes have the general formula RaSi(ORxe2x80x2)4-a wherein R is selected from the phenyl group, hydrogen, vinyl, or an alkyl group having from 1 to 12 carbon atoms, Rxe2x80x2 is selected from hydrogen, vinyl, or an alkyl group having from 1 to 8 carbon atoms and, a has a value of 1 or 2.
A further embodiment of the use of hydrolyzable silanes is a curable polymeric system comprising (i) a siloxane polymer or a mixture of siloxane polymers having an average of at least two silanol groups per molecule and (ii) sufficient crosslinker to crosslink a significant portion of the siloxane polymer or mixture of siloxane polymers (i), and thereafter, curing the product of (I), wherein the crosslinker is selected from a group consisting of Rxe2x80x3Si(Oxime)3 and Rxe2x80x2Si(Oxime)4 wherein Rxe2x80x3 is selected from the phenyl group, hydrogen, vinyl, or an alkyl group having from 1 to 12 carbon atoms.
Yet another embodiment of this invention is a method of preserving organic and inorganic materials, in which the method comprises impregnating a material selected from organic materials and inorganic materials with (i) a siloxane polymer or a mixture of siloxane polymers having an average of at least two unsaturated groups per molecule; (ii) sufficient crosslinker or a mixture of crosslinkers to crosslink a significant portion of the siloxane polymer or mixture of siloxane polymers (i) wherein the crosslinker or crosslinkers are comprised of organosilicon compounds having at least two hydrogen atoms per silicon and are selected from the group consisting of (a) silanes, (b) siloxanes and (c) mixtures of (a) and (b) and, (iii) a platinum catalyst, and thereafter, (II) allowing the product of (I) to cure.
Finally, there is disclosed a method of configuring wood products, which method comprises (I) impregnating the wood product with a curable system and thereafter (II) configuring the wood product to a desired shape and (III), while maintaining the wood product in the configuration of (II), curing the curable system.
With respect to the inventive method herein, the term xe2x80x9cnegative pressurexe2x80x9d means without pressure and essentially in a vacuum, while the term xe2x80x9cpositive pressurexe2x80x9d denotes the absence of a vacuum. The examples herein describe negative pressure in inches of mercury and generally, 3 to 5 inches is a poor vacuum and thirty inches is considered to be a good vacuum.
The substrates utilized in the method of this invention are first subjected to a dehydration step in which any water in the in substrate is displaced, or is essentially displaced by a solvent or the like.
The general method used herein was a modified method of the method used by those skilled in the art. In general, samples were first dehydrated in acetone which was contained in a freezer mounted vacuum chamber (hereinafter xe2x80x9cFMVCxe2x80x9d). After dehydration, the samples were placed into the materials for impregnation, such materials being set forth in detail in the following examples. Each of the samples was treated by the impregnating material for a period of several hours as noted in the examples. The process can be found in detail with regard to Example 1 below.
The siloxanes used in these examples are the following unless otherwise noted in the example:
Siloxane 1=a siloxane having an average of two vinyl groups per molecule, essentially on the terminal ends of the molecule and having dimethylsiloxy units, said dimethylsiloxy units having a degree of polymerization of about 100.
Siloxane 2=a siloxane having an average of two hydroxy groups (silanol groups) per molecule, essentially on the terminal ends of the molecule and having dimethylsiloxy units, said dimethylsiloxy units having a degree of polymerization of about 100.
Siloxane 3=a hydroxy terminated siloxane as in Siloxane 2 except its degree of polymerization is about 3 to 5.
Siloxane 4=a hydroxy terminated siloxane as in Siloxane 2 id except its degree of polymerization is about 35 to 40.
Siloxane 5=a hydroxy terminated siloxane as in Siloxane 2 except its degree of polymerization is about 6 to 10.
Siloxane 6=a hydroxy terminated siloxane as in Siloxane 2 except its degree of polymerization is about 300.